The present invention relates to a thermo-compression-formed, layered panel structure, and in particular, to such a structure which features a special assembly of both thermoformable and non-thermoformable layer materials self-bondedly joined through what is referred to herein as being a differentiated-material, transition-discontinuity-style, thermally bonded interface, or thermal bond (also called a thermal-compression mechanical bond).
According to this invention, a generally planar, layered panel structure is created which, while, as just mentioned, being generally planar in nature, may have certain topographical surface features that may, at least partially, be compression-thermoformed during assembly of the layer materials which make up the panel structure. The panel structure produced by practice of the invention features a relatively low-density, low-cost, non-thermoformable, principal, generally planar body having opposite faces, to at least one of which faces is thermally compressively bonded to a face in a higher-density, typically-higher-cost, much thinner, fibre-strand-reinforced, thermoformable plastic skin. The body, as measured transversely between its opposite faces (its transfacial thickness), is thicker than the skin as also so measured.
The thermal compression, or thermal compressive, bond existing between these thermoformable and non-thermoformable materials in the panel structure of the invention is referred to variously herein as a self-bond to reflect the fact that, preferably, no additional bonding adhesive is employed. Rather molten plastic material from the thermoformable material per se flows to create the uniting bond between the materials, and a consequence of this structural bonding arrangement is that a finished panel structure performs throughout with just the two desired structural characteristics of only the selected thermoformable and non-thermoformable materials. This has proven, in many application settings, to be a functionally desirable characteristic of the structure of the invention, in that the inter-material, transition bond region per se does not exhibit the otherwise expectable, and perhaps somewhat unpredictable, load-managing behavior of a foreign bonding substance.
This layered assembly, i.e., the panel structure of the present invention, possesses useful overall dimensional bulk (i.e., mainly thickness) which is contributed chiefly by the transfacial thickness of the lower-density body (layer), along with elevated load-bearing strength which is furnished principally by the appreciably higher-density (to be discussed later herein), significantly thinner, strand-reinforced skin (layer). This skin, in addition to offering elevated load-bearing strength, as just mentioned, also affords a high degree of abrasion resistance.
These two different-thermal-characteristic materials may be surface-joined in different organizational ways in an overall panel structure made in accordance with the present invention. Two such surface-joined ways are specifically illustrated herein, including one wherein a finished panel structure is formed with just one-each layer of each of these two materials, and another wherein there is, in a finished panel structure, a central, or core, layer formed of the non-thermoformable material, united with a pair of opposite-side-cladding skin layers formed of the thermoformable material.
The self-bond union of these two materials, produced via a thermally compressively bonded interface described herein, as mentioned above, as being a differentiated-material, transition-discontinuity-style interface, produces a composite structural panel assembly which exhibits (a) the strength that one would typically and intuitively associate with a unitary, homogeneous structure having the thickness and bulk of the principal, non-thermoformable body material, and (b) the light-weightness that one would typically and intuitively associate with a unitary, homogeneous structure having the thinness and low, apparent bulk of the thermoformable skin material. These “intuitive” associations, of course, would most probably come about, at least in part, because of a lack of an initial understanding of the appreciably different layer-density and internal-strength characteristics that are correctly associated with the two different materials that have been chosen for use in the panel structure of the invention.
Additionally, thermoformability of the skin, and thermal bonding of the skin to the body, uniquely allow for the fabrication, in several different ways, of a structural panel having, if desired, a complex surface topography (a) dictated by either or both of (1) pre-shaping of the bonding face of the non-thermoformable body, and/or (2) modest thermal-deformation-compression of the thermoformable skin material, and/or (3) a combination of these two approaches. Where body-material pre-shaping is employed, such pre-shaping telegraphs easily into the final panel configuration of the skin because of the skin's naturally offered thermo-configurational-deformability that is enabled and invoked during thermal-compression bonding of the body and the skin.
Many applications exist for the structural panel of this invention, including within-building wall and door applications, such as garage-door and hurricane-door- and window-panel applications, truck and trailed bed applications, vehicle door-panel applications, boating-structure applications, and many others.
These and other features which are offered by the layered, composite panel structure of the present invention will become more fully apparent as the description of the invention which shortly follows this text, is read in conjunction with the accompanying drawings.